1. Field of the Invention
The present invention relates to a cryopump.
2. Description of the Related Art
A cryopump normally includes two kinds of cryopanels with different temperatures. Gases condense on a lower-temperature cryopanel. Along with use of the cryopump, a condensing layer grows on the lower-temperature cryopanel and can eventually contact a higher-temperature cryopanel. In this case, gases vaporize again at a contacting part between the higher-temperature cryopanel and the condensing layer and are released into the environment. Since then, the cryopump cannot play an actual role sufficiently. Thus, the total amount of gas condensed at this time provides a maximum amount of gas condensed in the cryopump.